An integral step in many processes or systems for the production of textile fibers has been the collection of a rapidly moving multifilamentary strand in a container for transport to the next processing step. This process, often called piddling or canning, has provided a means by which one or more filamentary strands (referred to herein as tow or rope) were collected and possibly combined before processing through a draw/crimp step, which is often performed at a speed that has generally been much slower than the previous step, such as, for example, spinning a synthetic polymer to form synthetic filaments. A long-standing problem in the piddling process has been how to deposit such a rapidly-moving line into the can in such a way as to avoid entanglements that may be a problem particularly upon subsequent removal of product from the can. Several methods are available commercially and/or have been published.
The system of piddling a textile rope that is currently preferred commercially involves using a pair of toothed rolls to pull a tow from the primary (withdrawal) spinning rolls. Such toothed rolls, often referred to as gear rolls, gear plaiters or sunflower rolls, are available on piddler systems marketed by IWKA, Neumag, and Fleissner, for example. In these units, the toothed rolls are intended to pull the tow strand from a previous roll and to release the strand in such a way that it (1) does not wrap any rolls, and (2) is distributed so as to land softly in the can. To accomplish the first objective (a low wrap potential), large diameter rolls are used with many teeth to provide a small fiber contact area at the tip of each tooth. To enhance release of the filaments, the teeth are often coated with a low friction material and the surface speed of the toothed rolls is often greater than the speed of the moving tow band to enable the teeth to slip over the fibers and to avoid developing too much static friction. A soft landing of the moving tow line into the can is caused primarily by converting a large portion of the velocity of the moving tow band into a horizontal component. This is accomplished primarily by intermeshing the teeth from the two adjacent rolls so that the tow band folds upon itself. The vertical component of the velocity is further reduced by the tendency of filaments to adhere intermittently and momentarily to the teeth, which can cause the band to pull off its centerline and/or to open. We have noted several problems with this type of piddler. Their use is often limited in practical operations to low speeds of less than 1000 m/min owing to the difficulty of moving such (large diameter) sunflower rolls at high revolutions; we have experienced increased incidence of wraps at higher speeds. In addition, for a given product, we have found that the operating range of this type of equipment can often be relatively narrow, especially with certain types of filaments. In many instances, we have found that a mesh between the rolls that is too loose will result in poor can lay and resultant tangles, while a mesh that is too tight will result in the tow line wrapping the sunflower rolls. Wraps have also frequently been caused by wear and chipping of any low friction coating applied to the tooth surfaces. The higher speed of the sunflower roll teeth relative to the fibers can also result in broken filaments, which in turn can lead to dark dyed sections in subsequent fiber or fabric processing. Sometimes maintaining tension between the sunflower rolls and previous rolls has also been difficult. The nature of this type of piddler requires that only a light force be imparted on the filaments by the faster moving sunflower rolls since it is not desired to stretch the filaments at this point and since the higher speeds and/or tighter roll mesh required to give more tension can also result in sunflower roll wraps. To summarize, various problems have been experienced in practical operation of the toothed roll systems that are available commercially and improvements are desirable, especially when processing certain specific types of filaments on such toothed roll piddler systems.
Disclosures of using a pneumatic jet for depositing textile tows date back almost 50 years, e.g., Koster in U.S. Pat. No. 2,447,982, Burns in U.S. Pat. No. 2,971,243, King et al in U.S. Pat. No. 3,706,407, and Goodner in U.S. Pat. No. 3,387,756. All of the above prior suggestions for using a pneumatic (or aspirating) jet have required rotating mechanical parts and angling of a discharge tube away from the tow line's vertical inlet position, which require complex apparatus, often in relation to rotating air joints and seals, and their maintenance. We believe that such air jet piddlers are not being offered commercially now, although they had been suggested in the art and had been offered in earlier years, before gear piddlers became favored. Koster deposited his continuous filamentary material 2 in the form of a heaped coil or numerous staggered, partially over-lapping loops (col 1, lines 23-26) by passing his filamentary material with a stream of fluid through an outlet tube 11 that had a bend at 12 (so that the lower portion was angled) and a second bend at 13 so that discharge of the fluid caused rotation of tube 11 (col 2, lines 1-34 and the drawing). Burns referred to prior methods of blowing textile material through a tube revolving about an axis to deposit the textile material in the form of piled or over-lapping loops or coils and warned about difficulties caused by entanglement of filaments and obtaining "non-uniformly drawn sections" and so Burns' objective was to deposit his filaments without looped or entangled filaments so the filaments in his tow bundle would remain essentially parallel (col 1, lines 1-41). Burns used an air jet 5 that was rotated to discharge the tow at an angle in the form of a helical coil (e.g., col 2, especially lines 19-25 and FIG. 1). Burns emphasized placing his air jet 5 at the delivery end of his rotatably mounted apparatus and warned that attempts to operate with the jet in the vertical path of travel of the tow bundle had always led to excessive amount of entanglement (col 3, lines 58-67). Goodner is entitled "Pneumatic Jet Tow Piddler", requirements then being to propel heavy denier tows at high speeds while simultaneously laying (them) in coils, by spirally dispensing them into large containers or cans (col 1, lines 10-17). Goodner used a rotatably mounted jet with a nozzle 22 having a curved end to effect deposition in coils (e.g., col 2, lines 59-65 and FIG. 1). King referred to Koster and Burns, and talked of the need for a rotating drive (as used by Burns, rather than Koster's technique) to avoid disruptive air currents that would disturb the more or less parallel relation of the filaments that was considered desirable and the need to avoid any fiber-catching joint (e.g., col 1, lines 22-58).
What is notable, in retrospect, was that the desire to avoid entanglement of the filaments was naturally associated in the minds of those skilled in the art with the desirability of preserving the essentially parallel relation of the filaments which seemed to them to mean that the tow bundle should be kept integral in separate coils, i.e., that filaments from one coil should not be allowed to intrude into another coil and entangle, which caused problems when the tow was later withdrawn from the can.